Change the way we display available Syntaxes in Administration

Go to http://localhost:8080/xwiki/bin/admin/XWiki/XWikiPreferences?editor=globaladmin&section=Syntaxes

You can see a list of DISABLED SYNTAXES with all of them checked except XWiki 2.1.

I think this display is counter intuitive for the user. It would be better to have a list of "Enabled Syntaxes" with only XWiki 2.1 enabled by default.

See the attached screenshot for a proposal.